Video projector technology continues to advance pixel resolution and light output levels with ever more capable display solutions. Lower device costs have also expanded utilization of these products. These trends are further influenced by techniques developed to seamlessly combine multiple projectors to form even larger and brighter displays. Such multi-device displays can now be created with shape and dimension capabilities far greater than the capabilities of a single device or with less cost than comparable single projector solutions.
Projectors typically have a variety of inputs for receiving source content to display. Video standards have defined a growing number of connectors and signaling formats ranging from older analog Composite, Separate Video (S-Video), and DSUB-15 through digital visual interface (DVI), high definition multimedia interface (HDMI), and DisplayPort. Network connections, memory cards, portable storage devices, and other interfaces can provide digital media in a variety of formats and through various protocols. Some projectors may have internal storage capabilities that allow for presenting preprocessed document files, images, or other content preloaded into the device.
The range of signaling, input resolutions and aspect ratios makes matching source content to display output capabilities an ongoing challenge. Generally, when source content resolution equals a device's native pixel resolution, higher output quality is achieved. Content scaling, cropping, or positioning output on only a portion of the display's pixel area are common operations employed by display devices. With larger displays composed of many projectors, the ideal “native” resolution is less clear. Virtual resolutions formed by the combined devices, each with a respective native resolution, create displays that may easily surpass the pixel dimensions or aspect ratios of the most common source content formats.
In an example business conference room environment, laptops are often physically brought and connected to a projector with a video cable to display source content. Personal computers (PCs) may be dynamically disconnected and others cabled in turn as demonstration content shifts among presenting participants. Cable reshuffling distracts the presentation flow and cable connector incompatibilities among devices can hamper progress of the presentation. Some projectors aide this situation by providing multiple input ports and connection types which can allow cabling of several PCs at once and provide user switching among the differing source inputs when required. In another environment, a single presentation PC is connected to the projector and content is required to be preloaded into the presentation PC, or accessed via a network connection, for the presentation. This environment requires time to transfer files and suggests sharing of the content on a public device.
A direct physical PC video connection to a projector allows display of the host operating system desktop and applications as the source content. The PC video card configuration determines the signal resolution. Network capable projectors may even provide interfaces to view content on the network or provide a mechanism to stream content, like the PC desktop, to the projection device. In all cases, resolutions of each connected device desktop vary and often do not match the ideal resolution of the projector. Projectors employ a scaling method to fill the output screen which can also introduce unwanted artifacts. In a large scale display, such as with a display from a multi-projector system, content from a device is typically always scaled to fit the large scale display resolution or otherwise presented within a bounded region on the display surface. The connected source device is not aware of the large scale display resolution or the scaling performed by the projection system and consequently limitations are imposed on the eventual large scale display.
It is within this context that the embodiments arise.